Torque indicating wrench



May 2l, 1940..r W. c. KREss TCRQUE INDICATING WRENCH Filed May 14, 195s ORN S JN @WSN Patented May 21, 1940 PATENT OFFICE TORQUE INDICATING WRENCH Willard C. Kress, Kenmore, N. Y., assigner' to J. H. Williams & Co., Buffalo, N. Y., a corpora.-

tion oi` New York Application May 14, 1938, Serial No. 207,892

5 Claims.

My present invention relates to a torque indicating or measuring wrench and aims to provide certain improvements therein. More especially, it constitutes an improvement upon my co-pending application, Serial No. 131,547, filed March 18. 1927.

Torque indicating or measuring wrenches have been heretofore proposed for indicating applied predetermined measured force in tightening capscrews, bolts, nuts and the like and the various applications thereof,V and have recently found particular favor in the tightening of cap-screws or studs for holding down the heads of engine cylinders, the studs oi which, if tightened unequally, cause distortion in the cylinder blookand give rise to motor failure. In fact, many failures in motor rebuilding and cylinder block reboring jobs have been definitely traced to the unequal tightening of the cylinder head studs.

The torque indicating or measuring wrenches heretofore proposed, with which I am familiar, have either used spring or fluid pressure means for resisting and measuring thetorque applied to the relements being rotated, and all of these devicesv are either complicated in construction or cumbersome and unwieldy in use.

The torque indicating wrench disclosed in my copending application, above mentioned, is based on the principle of measuring the vdeflective torque on the shank or operating handle of the wrench when applying turning force to a rotatable element and embodies a handle provided at one end with means for driving or rotating a cap-screw, nut, bolt or the like and has attached to the driving means a rigid arm extending in parallel spaced relation to the handle, and having at its opposite end a shoulder for cooperation with the follower of a gauge carried by and movable with the handle for indicating the deflective torque of the handle under operating load. While this form oi.' torque indicating wrench has proved satisiactory in principle, my inability to secure a reliable dial gauge which could be built into the tool 1so that it could be sold at an attractive price has been the primary obstacle which has stood in the way of commercial production of the device.

According to my present invention, I have overcome the difficulty recited in the preceding paragraph and have greatly simplified the construction oi the wrench by providing the gauge means directly on the operating handle and the cooperating arm and I secure the necessary magnification of the indication of the flexing of the handle under operating load by means of the oblique registry of a scale on one of the members with an index on the other of said `members. This arrangement I have found to be both convenient and suliiciently accurate for wrench purposes.

My present application discloses two preferred embodiments of my invention, the constructional and operative features of which will be apparent from the detailed description which follows when considered in conjunction with the drawing wherein:

Figure 1 is a top plan view of a torque indicating wrench embodying my invention;

Fig. 2 is a side elevation of the wrench shown in Fig, l. with parts broken away Fig. 3 is a .detail of the index member wrench shown in Fig. l;

Fig. 4 is a section taken along the plane of the line 4-4 of Fig. 3;

Fig. 5 is a section taken along the plane of th line 5-5 of Fig. l;

Fig. 6 is a top plan view oi another embodiment of my invention;

Fig. 7 is a side elevation of the wrench shown in Fig. 6; and

Fig. 8 is a section taken substantially along the line 8--8 of Fig. 7.

Referring first to Figs. 1 to 5 of the drawing, the torque indicating wrench shown therein coniprises a handle I which has xedly connected to one end thereof a driving head il which, on its underside, is provided with a square shank I2 having a spring pressed ball or other conventional means I3 for engaging in and driving a detachable socket (not shown) which is adapted to engage the head of a cap-screw, a looltor a nut for rotating the same. The opposite end of the Ihandle ID is formed with a hand gripping portion I4 which may be suitablyknurled or oth-`- erwise provided with a surfacel which will permit a gripping engagement thereof. Mounted on the handle adjacent the gripping portion thereof is an inde-X member I in the form of a flat strip of metal which is secured to the handle in any preferred manner, for example, by Vfastening screws I6. The index member is formed on its top surface with a rabbeted or cut-away portion I'I which divides the top surface into two triangular portions, the common side I3 of which triangles provides an index or gauge line. To emphasize the character of this index line, the cut-away or rabbeted surface may be contrastingly colored to the normal surface of the member and preferably the rabbeted surface is coated with black enamel.

of the face 28 which carries a scale 29.

spaced relation to the top of the handle ID is a rigid member or arm I9 which at its end adjacent the gripping portion of the handle lies in.

substantially overlapping contacting' relation to the index member II and is provided with a scale 20, the edge 2I of Which is intended for cooperation with the index I8. 'I'o facilitate the reading on the scale with respect to the index the portion of the member I9 which carries the scale is bevelled, as shown at 22.

From an inspection of Figs. 1 to 5 it will be apparent that the index and the scale each extend longitudinally of the respective members upon which they are formed and are disposed in converging relation to each other and thus provides a magnifying means for indicating the relative relation between the scale `and the index due to the flexing of the handle I0 under an operating load.

In the use of the wrench hereinbefore described the shank I2 will engage within and hold a socket member (not shown) in assembled relation on the driving head, and upon engaging such socket with the head of a cap-screw, a bolt, a nut or the like it will be apparent that by gripping the handle portion III and moving it through an arc with the socket head as a pivot, the capscrew, bolt or nut will be rotated and thereby fastened onto its complementary part. As the rotatable element, namely the cap-screw, bolt or nut is brought up into tightened relation with its cooperating part, it will be apparent that the handle II) will iiex or be deflected under the force of tightening the rotatable element as shown in dot and dash lines in Fig. 1. This deflection in the handle, however, is not imparted to the rigid member I9 and hence as the handle Ib flexes in moving in a clockwise direction, the index I8 thereon will ride under the scale 2!) and cooperate with the edge thereof to indicate the force applied to the rotatable element. The scale may be calibrated in inch-pounds, or other desirable units and thereby provide a direct reading for the torque applied to a rotatable element. The wrench will be capable of giving an infinite number of accurate readings of deflection torque so long as the handle is not stressed beyond the elastic limit of the stock from which it is made. It will thus be apparent that I have provided an exceedingly simple torque indicating wrench which is especially useful in the automotive trade for the purpose of applying equal stress to all of the cap-screws or bolts for tightening down the cylinder head on an engine block or for any other purpose where a predetermined or uniform tightening of the elements is required for a given job, it being merely necessary, for obtaining such uniformity, to tighten the element to the same reading onthe scale.

In the modification of my invention shown in Figs. 6 to 8 the operating handle 2d is provided at one end with a driving head 25 cuite similar to the driving head II, and the rigid arm .".6 is formed integrally with the handle by bending back a portion of the stock from which the lian-- dle is formed. The free end of the bent-back arm is made to terminate in close proximity to the driving head 25 and is formed with a reduced flattened portion 2'! whichoverlies the top of the handle and is formed with a bevelled top Normally the extreme tip of the inner side of the scale terminates at the center line at the top of the handle,

which center line may be indicated by a score line or narrow groove 30 which may be filled with coloring material to accentuate it. To bring the inner edge of the bevelled portion of the arm into overlying relation with the top of the handle at the index portion thereon, the arm 26 is slightly offset, as best shown in Fig. '7. In the use of the embodiment of my invention, illustrated in Figs. 6 to 8, the action is substantially the same as that hereinbefore described with respect to the wrench shown in Figs. 1 to 5, and merely differs therefrom that in the application of a force to the hand engaging the end of the handle 2d in the course of moving it through an arc with the socket head as a pivot, the deflection lin the handle will cause a movement of the index line 30 relatively to the oblique edge of the scale 28 to provide an indication of the torque applied to the wrench, as shown in dot and dash line in Fig. 6.

From the foregoing detailed description it will be apparent that both embodiments of my invention incorporate a method of magnifying the deflection in a wrench handle produced by the application of torque thereto through the medium of the oblique registry of a scale with an index whereby a torque reading may be directly had.

and although this reading may not be absolutely accurate, it is sufficiently so for most purposes.

It will also be appreciated that the means which il' I have provided are devoid of springs, iiuid pressure means or complicated and costly gauging units and thus enable me to provide a wrench of the class described which is exceedingly simple in construction, economical to produce, and whichy has no movable parts subject to becoming dislodged or broken.

Notwithstanding that I have shown and described two embodiments of my invention, I do not wish to be limited to the specific details of construction set forth herein, since it will be apparent to those skilled in the art that other modications may be resorted to without departing from the spirit of the invention.

What I claim is:

1. A measuring instrument comprising two juxtaposed relatively rigid members rigidly connected together at one end and being unconnected at their other ends, said members extending in substantially parallel relation to each other, at least one of said members being capable of being iiexed laterally with respect to the other under applied force, the unconnected ends of the members being in superposed relation and provided one with a scale disposed longitudinallyof the fi member and the other with an index disposed longitudinally of the member for cooperation with the scale and adapted to indicate the degree to which one of. the members has been flexed by the application. of applied force.

2. A torque indicating Wrench comprising an operating handle capable of flexing under operating load. driving meansy at one end of the handle for engaging and rotating a rotatable element, a rigid arm extending in spaced super posed substantially parallel relation to the handle, one end of said arm being rigidly connected to the handle and the other end of said arm Abeing free, the free end of said arm and the juxtaposed end of the handle being provided i and adapted for indicating the deflective torque on the handle as the uncovering of the members at the indicating ends thereof takes place when applying the turning force to a rotatable element to which the driving means of the Wrench is applied. l

3. A torque indicatingwrench comprising an operating handle capable of exing under operating load, driving means at one end of the handle for engaging and rotating a rotatable element, a rigid arm extending in spaced juxtaposition to the handle, one end of said arm being rigidly connected to the end of the handle having the driving means and the other end of the arm being free, the free end of said arm and the juxtaposed end of the handlev being in superposed relation and provided one with a scale and the other with an edge adapted to serve as an index for cooperation with said scale and adapted for indicating the deflective torque on the handle when applying turning force to a rotatable element, the index and the scale each extending longitudinally of the respective elements upon which they are carried.

4. A torque indicating Wrench comprising an operating handle capable of flexing under operating load, driving means at one end of the handle for engaging and rotating a rotatable element, a rigid arm extending in spaced juxtaposition to the handle, one end of said arm being rigidly connected to the force applyingl end of the handle and the other end of said arm being free, the free end of said arm and the juxtaposed end of the handle having the driving means being provided one with a scale and the other with an index for cooperation with said scale for indicating the deflective torque on the handle when applying turning force to a rotatable element, the index and the scale each extending longitudinally of the respective elements upon which they are carried and being vdisposed in A converging relation to each other.

5. A torque indicatingwrench comprising an operating handle capable of iiexing under operating load, driving means at one end of the handle for engaging and rotating a rotatable element, an arm integrally formed with the handle by bending back a portion of the stock from which the handle is formed, the free end of said bent back arm terminating in close proximity to the endof the handle having the driving means and said arm and handle at said last mentioned ends being provided one With a scale and the other with an index for cooperation With said scale for indicating the deiiective torque onthe handle when applying turning force to a rotatable element. y

` WILLARD C. KRESS. 

